CODEWITHSUNDEEP
cmacros
Danijel
Danijel

Reputation: 8606

Generating `#define`s from a macro

// define 31:
#define f_Q31(x)                      f_Q(31,x)
#define q31_F(x)                      q_F(31,x)
#define CHECK_Q31(q,def)              CHECK_Q(31,q,def)
// define 25:
#define f_Q25(x)                      f_Q(25,x)
#define q25_F(x)                      q_F(25,x)
#define CHECK_Q25(q,def)              CHECK_Q(25,q,def)
// etc.

Can the above be generalized, like so: 

#define SUPPORT_TYPE(N) something?

Adding a new type would then be a one line:

#define SUPPORT_TYPE_Q31   SUPPORT_TYPE(31)
#define SUPPORT_TYPE_Q25   SUPPORT_TYPE(25)

Upvotes: 1

Views: 223

Answers (1)

Jean-François Fabre
Jean-François Fabre

Reputation: 140148

Preprocessor only has one pass, so you cannot generate #define statements with other #define statements.

You could use a small script (python comes to mind, surprisingly :)) to do what you want:

text="""// define {0}:
#define f_Q{0}(x)                      f_Q({0},x)
#define q{0}_F(x)                      q_F({0},x)
#define CHECK_Q{0}(q,def)              CHECK_Q({0},q,def)
"""

for i in (25,31):
    print(text.format(i))

when running this script it generates:

// define 25:
#define f_Q25(x)                      f_Q(25,x)
#define q25_F(x)                      q_F(25,x)
#define CHECK_Q25(q,def)              CHECK_Q(25,q,def)

// define 31:
#define f_Q31(x)                      f_Q(31,x)
#define q31_F(x)                      q_F(31,x)
#define CHECK_Q31(q,def)              CHECK_Q(31,q,def)

Upvotes: 3

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